Scattering Life Through the Cosmos

by Paul Gilster on May 1, 2008

Olaf Stapledon’s Last and First Men (1930), amongst other wonders, pictures our descendants millions of years hence moving from world to world as they attempt to save the species. The Moon approaches the Earth, an imminent peril the ‘Fifth Men’ escape by terraforming Venus, unfortunately destroying indigenous life forms there. Later, the Fifth Men move on to Neptune, and when their existence there is endangered, they make an attempt to save themselves as a species by seeding their cells among the stars. Interestingly enough, Francis Crick (famed as a co-discoverer of the structure of DNA) suggested in 1973 that life could have been intentionally sent from elsewhere in the universe with the express purpose of finding a new home, an idea that made the later work of Fred Hoyle and Chandra Wickramasinghe seem positively tame.

We’re talking panspermia, the idea that life can survive long journeys through space to seed other planets (a notion Hoyle addressed in 1982’s Evolution from Space). The apotheosis of the concept is in the realms between the stars, as Stapledon and Hoyle both assumed. We already know that materials, though not necessarily life, can move between planets in our own Solar System, as shown by compelling evidence for Martian meteorites. But interstellar journeys are of another order, the distances so vast that the question of survival dominates the debate.

Yet comets could be interesting places for microbes to thrive, and it’s not beyond the bounds of possibility that an ejected comet might make its way between the stars, finally encountering another stellar companion and making a spectacular arrival upon a warm, rocky planet. There is no way at this juncture to prove whether or not life began on Earth this way, but it’s a concept that demands study. One way to investigate it is to work with microbes in near-Earth orbit, as a Japanese team now proposes to do aboard the International Space Station in an experiment called Tanpopo.

Image: Is panspermia a viable option for moving life not only between planets but also between the stars? Credit: Jess Johnson/UC Santa Cruz.

The discovery of microbes in space would hardly prove the concept of panspermia, for any materials at these altitudes could well have come from Earth. But a positive result could tell us more about how life manages to persist in the most hostile environments. The Tanpopo (‘dandelion’) experiment will examine tiny particles captured onto an aerogel, returning them to Earth for study of their makeup and possible microbes. Survival at ISS altitudes would definitely give panspermia advocates a boost while forcing us to contemplate the possibility that life began elsewhere.

After all, infalling material reaching Earth’s surface from space amounts to tens of thousands of tons on a yearly basis. Tanpopo is unlikely to show us any extraterrestrial microbes, but the researchers do plan, as a second part of the experiment, to expose Earth microbes to space on metal plates placed outside the ISS, as this story in New Scientist explains. The microbes will remain outside the station for periods of one to five years. some protected by clay minerals, some openly exposed to the rigors of the vacuum.

The experiment is slated to begin in 2011, offering a useful follow-up to work performed in 2002 by an ESA team using the Russian Foton satellite. Those remote controlled experiments exposed 50 million unprotected spores of the bacterium Bacillus subtilis to space, mixing another set of 50 million with particles of clay, red sandstone and other materials. The unprotected spores died quickly, but the protected ones produced numerous survivors, particularly those in the red sandstone mix. An exchange of biological materials between planets could not be ruled out by this experiment.

So we’ll see what Tanpopo comes up with as it goes to work on a highly resistant microbe called Deinococcus radiodurans, known to fend off ultraviolet and gamma radiation and to survive extreme dryness and vacuum. The project, which was presented at the recent Astrobiology Science Conference in Santa Clara CA, may offer yet more proof of life’s survival in hostile environments, but it will surely leave the question of the origin of that life open to further debate. Backing out to the big picture, it may be a long time before we identify microbes within a comet, but finding such evidence would keep interstellar panspermia in the picture, with obvious repercussions for life’s chances around other stars.

The possibility of forming multiple genetic lineages of humanity is intreguing as we colonize the galaxy and hopefully the local super cluster and then beyond. It would be interesting to see how human settlements evolve to adjust to their respective political, social mores, custums, and biospherical conditions on the planets they inhabit.

It would be interesting to see a human colony developed in some remote neck of the woods in the Amdromedea Galaxy and then come back 1 million years later to measure their average and maximum IQs, the psychological profiles of randomly selected individuals, their athletic abilities etc. It would be a great antropology experiment.

For directed panspermia, if we wanted to spread life through the galaxy I think that we’d want that life to include us…humans, not just bacteria. For me it wouldn’t be enough to send bacteria with the thought that one day billions of years later there would arise some intelligent creature that may be completely unlike us. Why not send the whole package including humans and create an instant fully developed biosphere with intelligent creatures that we could communicate with. So this line of logic would argue against the idea that we were intentionally seeded with bacteria long ago.

Unintentional panspermia though would be a different matter. It would hard for me to imagine a multi-cellular organism ever getting into the center of a comet so it seems as though bacteria would be the only reasonable passenger.

Just writing out loud here…but could could we genetically engineer Deinococcus radiodurans to carry DNA of other species (maybe even parts of human DNA), let it be blasted by radiation on an interstellar journey and then reassemble? Let it reproduce and separate as certain cells get wiped out by micrometeorites. In this way DNA of any species could be preserved indefinitely and then inserted into an appropriate cell at destination and then grown or gestated in stem-cell originated wombs. It would require biotech further than what we have now but something that looks feasible in the moderate-term. This would reduce our need for shielding of biologic material.

The Astrobiology Science Conference, recently held in
Santa Clara, California, was a complex universe teeming
with topics and ideas. Although there were far too many
interesting presentations to cover in full, this overview
provides a few highlights.

Further to James and John, and in a way also further to the Fermi/Great Filter duscussion:
although my impression is that the above article is actually more about natural/unintentional panspermia, the really interesting challenge for future humans could be to become instrumental in intentional forms of panspermia: seeding earthly and derived lifeforms across the Milky Way galaxy and beyond.
Triggered by the recent Fermi/Great Filter duscussion I have been thinking about this a bit further; regardless of how many planets with (primitive and complex) life there are in our galaxy, which is still the realm of speculation, it is more like a statistical likelihood that there must be many terrestrial planets with (potentially) favorable circumstances for (earthlike) biological life: water, right temperatures, (terraformable) atmosphere.
In other words: even in the most unfavorable case with regard to biological life in our galaxy (i.e. extreme rarity), we could say that for every planet with life there are many, many others potentially suitable for our types of life (or genetically engineered life).
As long as there are sunlike stars and terrestrial planets (and there are) I tend to be optimistic, stating that even bad news would be good news: either there is life out there, or *we* are going to bring it.

One of the great unsolved mysteries of science is the origin of life. How did it happen?

If we were able to click on Google Earth and visit the Earth during the Archean Eon, we would likely not recognize it is the same planet we inhabit today. The atmosphere was a reducing atmosphere of methane, ammonia, and other gases which would be toxic to most life. Also during this time, the Earth’s crust cooled enough that rocks and continental plates began to form.

It was early in the Archean that life first appeared on Earth. Our oldest fossils date to roughly 3.5 billion years ago, and consist of bacteria microfossils. In fact, all life during the more than one billion years of the Archean was bacterial.

We also know that the long period of Earth history prior to the advent of skeletons was punctuated by enormous mass extinction catastrophes that decimated the biota of our planet without a record. The early mass bombardment period 4.6 to 3.8 billion years ago is believed to have sterilized Earth’s surface at least several times. The rise of oxygen 2.4 to 2.2 billion years ago also certainly doomed most anaerobic bacterial species.

Through most of the 20th century, scientists thought that life began with a stupendous chemical fluke, unique in the observable universe.

Today, as physicist and astrobiologist Paul Davies of Arizona State University, points out it is fashionable to say that “life is written into the laws of nature – easy to get started and therefore likely to be widespread in the universe. The truth is, nobody has a clue. It could be either extreme, or somewhere in the middle.”

We may soon find the key in the discovery of a second genesis on another planet such as Mars, Davies goes on to say. There is an easier and more startling possibility, however, that is the thesis of Davies research paper Second Genesis, co-authored with Dr Charley Lineweaver of the Planetary Science Institute, Research School of Astronomy and Astrophysics, at Australia’s Mount Stromlo Observatory :

“If life really does form readily then we might expect it to have started many times over on Earth. There could be alien microbes right here, under our noses. Most life is microbial, and you can’t tell just by looking whether a microbe is “our” life or alien. You need to analyze the chemical innards. The search for terrestrial aliens has only just begun. If they are here, they could be identified soon. And the discovery that all life on Earth did not, after all, have a common origin would virtually prove that we are not alone in the universe.”

Larry’s news piece is interesting and quite right, especially with all the alternatives to DNA and standard codons that molecular biotech is revealling to us. The National Academies report from a year or two ago is well worth a peruse in this regard – they cover all the possible biosolvents, including supercritical gases, plus gas phase and solid phase life.

My personal feeling is that we’ve barely scratched the surface of the possible and our style of DNA/RNA life is but one variant frozen in by the peculiarities of planet Earth. But will we recognise alien life? Look at the furore over “nanobacteria” which now seems to have settled on them being “calcifying macromolecular complexes” – yet ones that seem to “replicate” and grow. Hmmm… we have a lot to learn.

Moffett Field CA (SPX) Jun 27, 2008 – Some scientists believe that at least one meteorite found in Antarctica preserves evidence of ancient life on Mars. Now, work by a team of English scientists reinforces an earlier suggestion that evidence of life on the early Earth might be found in meteorites on the moon. The original idea was presented in a 2002 paper by University of Washington astronomer John Armstrong, who suggested … more

Comedy Central announced Monday that the host of The Colbert Report will have his DNA digitized and sent to the International Space Station (ISS). According to the Associated Press, Stephen Colbert’s gene package will be carried there by famed video game designer Richard Garriott, who will travel to the station in October.

Garriott will deposit the “Immortality Drive,” a time capsule that will include human DNA and records of humanity’s greatest accomplishments, along with personal messages collected specifically for the project.

This will be the second time Colbert goes intergalactic. In May, he was the first late-night host to interview an astronaut, Garrett Reisman, while he was in space.

In a statement, Stephen Colbert said he was thrilled to have his DNA shot into space, as this would bring him “…one step closer to my lifelong dream of being the baby at the end of 2001,” referring to the 1968 sci-fi movie 2001: A Space Odyssey.

In a statement, Garriott said: “In the unlikely event that Earth and humanity are destroyed, mankind can be resurrected with Stephen Colbert’s DNA. Is there a better person for us to turn to for this high-level responsibility?”

Stephen Colbert’s answer to that rhetorical question would probably be “no.”

Charter

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last nine years, this site has coordinated its efforts with the Tau Zero Foundation, and now serves as the Foundation's news forum. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

On Comments

Centauri Dreams publishes selected comments on the articles under discussion here. The primary criterion is that comments contribute meaningfully to the debate. Among other criteria for selection: Comments must be on topic, directly related to the post in question, must use appropriate language and must not be abusive to others. Civility counts. In addition, a valid email address is required for a comment to be considered. Centauri Dreams is emphatically not a soapbox for political or religious views submitted by individuals or organizations. A fuller statement of the policy can be viewed on the Administrative page.